usually mulch is aplied at 3 inches thick,
the easy way the find out how much mulch you would need, measure LxW and that will give you the sq. ft. as for the amount of mulch needed one yd of mulch applied at 3 inches thick will cover 108sq ft ...

It's LxWxD divided by 27sq'=yds needed,
If your spreading it 3"then x by 3 ...if 2"then x by 2....ect,you don't minus the crown habit foliage of the plantings just say 4" to 6" circumfrence per plant.It's easy to remember minus 2' for every 4 plants.So if you have an 10x8bed and your spreading it 3" thick and there are 12 plants in the bed it would go like this 10x8x3=240 sq' -6'=234sq' divided by 27=8.66yds ...
and you order 9 yards anyway!

Generally I don't use all that equation stuff. I have learned to eye ball it perfectly. Landscaping is natural and not a perfect sience so enjoy it and you will make plenty of money..... :blob3: :blob3:

I think that guesswork can get some people into trouble, and not only that, but in some cases you will be called upon to show your estimates. At least in this state, to pass the landscape contractors exam you need to be able to look at a landscape design and figure out how much mulch and gravel to put down in various areas. Guessing won't work, and I'd think that the larger the job, the tougher it would be to guess exactly right.